The invention concerns an adjustable slalom pole, which consists of a standpipe, a ground part to be inserted in the ground and a tipping element to be arranged between the standpipe and the ground part.
In the adjustable slalom poles customarily being used today in the alpine skiing sport, the standpipe, found over the tipping point or the tipping zone, is made of thermoplastic synthetic material, and that is with generally the same diameter inside and outside. When the ski racer runs into such a slalom pole at high speeds and brushes away the pole with the knee, arm or hand or according to the newest slalom technique, with the leg of the boot or the lower thigh, then he experiences not only a more or less painful blow, but also the slalom pole behaves like a whip and irritates or even endangers the ski racer. The "whip effect" is a result of the very high speed at the time of contact of the racer. Due to forces or inertia which are essentially caused by the mass of the standpipe, the tip of the standpipe is impelled back shortly after the impact of the racer. The whip effect is especially typical for adjustable poles in which the course of bending moment from ground part to standpipe through the tipping zone is interrupted. Despite the whip effect, adjustable poles have been successful for slalom racing because a slalom pole without a tipping zone has other disadvantages, such as a greater strike effect on the racer and an easier pulling out of the ground anchoring.
It is the task of the invention to create an adjustable slalom pole in which the whip effect typical for adjustable slalom poles does not exceed a certain amount and at the same time meets the stresses to which an adjustable pole and its standpipe are subjected.
This task is solved, according to the invention, by making the standpipe of fiber-reinforced synthetic material.
The basis for the invention is the realization that the whip effect typical for adjustable poles is less the greater the bending resistance of a standpipe and the smaller its mass is. Due to the higher bending resistance of a standpipe made of fiber-reinforced synthetic material as opposed to a standpipe of thermoplastic synthetic material, a lower whip effect can therefore be attained with the aid of the measure according to the invention. The mass of the standpipe remains low due to the pipe construction, despite the increased bending resistance.
Due to the dependence on mass of "whip effect" it is also useful if the wall strength of the standpipe which consists of fiber-reinforced synthetic material tapers off preferably stepwise from bottom to top.
Experiments have shown that standpipes made of fiber-reinforced synthetic material attain the necessary bending resistance at very low wall strengths. In this case, the critical load is no longer the bending resistance, but the buckling strength of the pipe. The impact of the shier onto the standpipe takes place in an almost point-shaped fashion. In stiff standpipes the stress is very great; the standpipes can be dented and can snap off. It is therefore important to build these standpipes so that they are resistant to buckling. This can be achieved by filling the standpipes with foam or by orientating the reinforcing material with the fiber direction toward the circumference.
Despite the very solidly built slalom poles, it cannot be avoided that standpipes may break during falls for example. For these cases, care must be taken that the danger of injury is held as low as possible. In the case of the adjustable slalom pole according to the invention, this can be achieved advantageously in that at least the outer layer of the reinforcing material of the standpipe consists of such fibers which have a high elongation at fracture and no or low temperature dependence of this elongation at fracture. This is the case, for example, with aramide fibers or polyester fibers. Standpipes built in such a way will only bend off in the case of a break and the upper and lower ends stay together; there are no broken-off standpipes with an open beak point which can injure the skier.